Various systems and methods of data recognition are known to those skilled in the art, including portable systems for optically sensing and decoding data. Examples of such systems may be seen in U.S. Pat. No. 4,143,417 titled "Portable Data-Gathering Apparatus Formed by Modular Components Having Operate-Standby Modes" by Wald et al.; U.S. Pat. No. 4,521,678 titled "Battery-Powered Optical Bar Code Reader and Voltage Regulator Therefor" by Winter; U.S. Pat. No. 4,160,156 titled "Method and Apparatus for Reading Bar Coded Data Wherein the Light Source is Periodically Energized" by Sherer; and U.S. Pat. No. 5,189,291 titled "Bar Code Reader Operable as Remote Scanner or with Fixed Terminal" by Siemiatkowski. Portable systems have been used for data collection in a broad range of operations, including inventory control in retail stores and in the tracking of packages or cargo in the delivery industry. Portable optical reading units are typically battery powered or attached to a terminal station which supplies a power source.
Codes have been produced, and printed on products or containers, to increase the accuracy of such data collection systems. One such code is a "bar code" which may be read by passing an optical sensing unit over the bar code on the product or by passing the product over the optical sensing unit. A bar code typically consists of a pattern of black and white bars of varying widths, with the encoded information determined by the sequence of these varying width bars. Bars are scanned by the optical sensing unit and the widths of the bars are then translated into a specific identifying sequence for that particular item.
An optical sensing unit typically requires a source of radiation to illuminate the bar coded data which normally places a significant drain on the battery. As the applications of these portable optical sensing units continue to expand, users of such units continue to demand more capabilities, lighter weight, lower cost, and extended usage time from these units. Hence, the amount of power used by the radiation source, accompanying sensing, decoding, and other data processing circuits, data transmission circuits, and the display of decoded or user interface data continue to be a major obstacle in expanding applications.